On 12/27/2016 02:53 AM, Kirill A. Shutemov wrote:
We are going to switch core MM to 5-level paging abstraction.
This is preparation step which adds <asm-generic/5level-fixup.h>
As with 4level-fixup.h, the new header allows quickly make all
architectures compatible with 5-level paging in core MM.
In long run we would like to switch architectures to properly folded p4d
level by using <asm-generic/pgtable-nop4d.h>, but it requires more
changes to arch-specific code.
Signed-off-by: Kirill A. Shutemov <[email protected]>
---
include/asm-generic/4level-fixup.h | 3 ++-
include/asm-generic/5level-fixup.h | 41 ++++++++++++++++++++++++++++++++++++++
include/linux/mm.h | 3 +++
3 files changed, 46 insertions(+), 1 deletion(-)
create mode 100644 include/asm-generic/5level-fixup.h
diff --git a/include/asm-generic/4level-fixup.h
b/include/asm-generic/4level-fixup.h
index 5bdab6bffd23..928fd66b1271 100644
--- a/include/asm-generic/4level-fixup.h
+++ b/include/asm-generic/4level-fixup.h
@@ -15,7 +15,6 @@
((unlikely(pgd_none(*(pud))) && __pmd_alloc(mm, pud, address))? \
NULL: pmd_offset(pud, address))
-#define pud_alloc(mm, pgd, address) (pgd)
This...
#define pud_offset(pgd, start) (pgd)
#define pud_none(pud) 0
#define pud_bad(pud) 0
@@ -35,4 +34,6 @@
#undef pud_addr_end
#define pud_addr_end(addr, end) (end)
+#include <asm-generic/5level-fixup.h>
... plus this...
+
#endif
diff --git a/include/asm-generic/5level-fixup.h
b/include/asm-generic/5level-fixup.h
new file mode 100644
index 000000000000..b5ca82dc4175
--- /dev/null
+++ b/include/asm-generic/5level-fixup.h
@@ -0,0 +1,41 @@
+#ifndef _5LEVEL_FIXUP_H
+#define _5LEVEL_FIXUP_H
+
+#define __ARCH_HAS_5LEVEL_HACK
+#define __PAGETABLE_P4D_FOLDED
+
+#define P4D_SHIFT PGDIR_SHIFT
+#define P4D_SIZE PGDIR_SIZE
+#define P4D_MASK PGDIR_MASK
+#define PTRS_PER_P4D 1
+
+#define p4d_t pgd_t
+
+#define pud_alloc(mm, p4d, address) \
+ ((unlikely(pgd_none(*(p4d))) && __pud_alloc(mm, p4d, address)) ? \
+ NULL : pud_offset(p4d, address))
... and this, makes me wonder if that broke pud_alloc() for architectures that
use the 4level-fixup.h. Don't those need to continue having pud_alloc() as (pgd)?
